Ore-roasting furnace



H. A. CLARK, F. HILL AND A. G. McGREGOR.

05E HOASIING FURNACE. APPLICATION FIL'ED JULY,I9. 1920.

Patented June 7; 1921.

4 SHEETS-SHEET l- H. A. CLARK, J. HILL AND A. G. MCGREGOR. ORE RQASTING FURNACE.

APPLICATION FILED JULY 9,1920.

1,380,529. Patented June 7, 1921-.

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- w M w H. A. CLARK, J. F. HILL AND A. GfMcGREGOR. ORE ROASTING FURNACE.

APPLICATION FILED JULY 19.1920. 1,880,529.

Patented J @6 7, 1921.

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.ifiw 8 15 I f 1.9 i116 H. A. ,CLA'RK, J. F. HILL AND A. G. McGREGOR.

ORE ROASTING FURNACE. I APPLICATION FILED JULY 1-9. |920.

Patented June 7, 192-1..

4 SHEETS-SHEET 4- mmsz a UNTTEQ STATES HARRY ALLEN CLARK AND J OHN FRANCIS HILL, OF DOUGLAS, AND ALEXANDER GRANT INTCGREGOH, OF WARREN, ARIZONA.

ORE-ROASTING FURNACE.

Specification of Letters Patent.

Patented June *7, 1921.

Application filed July 19, 1920. Serial No. 397,371.

To all whom it may concern Be it known that we, HARRY ALLEN CLARK and JOHN FRANCIS HILL, of Douglas, Arizona, and ALEXANDER GRANT Mo- GREcoR, all citizens of the United States, residing, respectively, at Douglas and Warren, in the county of Cochise and State of Arizona, have invented or discovered certain new and useful Improvements in Ore- Roasting Furnaces, of which the following is a specification, reference being had therein to the accompanying drawings.

This invention relates to an improvement in ore roasting furnaces of the Wedge or Hereshoif type, comprising a series of hearths, one above the other, and to which the ore is successively fed from the top of the furnace, this downward feed of the ore in the furnace being efiected by rakes or rabbles mounted on arms carried by a central rotating shaft.

When the ore to be roasted contains 25% or more of sulfur it can generally be roasted without adding outside fuel after the furnace is heated up at starting. With this amount of sulfur sufiicient heat is generated to drive off the moisture and ignite the sulfur by the time it gets to about the third hearth, but in ores having too much moisture or not enough sulfur it is often necessary to introduce added fuel to the furnace. Sometimes coal has been added to the ore to overcome this trouble; but a more efficient method, however, has been to employ a fire box, the heated gas from the fire box pass ing through an opening in the shell of the furnace. Also it is common to place an oil burner in the furnace wall above one of the hearths so that a mixture of oil and air. will be discharged into the furnace just inside of the furnace lining. These furnaces generally have doors, constructed circumferentially around the shell, for each hearth. *It is common practice to put the oil burner through one of these doors. Also in a similar way powdered coal is sometimes fed to the inside of the furnace. The fuel is generally admitted into the furnace just above the next to the bottom hearth. If fire boxes are used they are generally an ranged so that gases from them are taken into the furnace on the hearth next to the bottom.

There are, however, objections to these methods of applying fuel to roasting furnaces, and which objections we aim to overcome by our improvements. With the center shaft revolving with its arms and rakes or rabbles and the crushed ore dropping from hearth to hearth, considerable dust is raised in the furnace, so that when the fuel is applied to the furnace at one place, as has been the practice heretofore, crusts and accretions pile up on the lower side of the hearth just above the flame. It is necessary to break off these accumulations from time to time, but even with a great deal of care there is generally an accumulation over the flame. This accumulation weighs down the hearth and often causes it to sag, and repairs on this account are necessary from time to time.

These roasting furnaces are often installed so that there are as many as sixty roasters in one building, and one man may be called upon to look after eight roasters. Sometimes, due to an interruption in the power, a break in the power transmission system, or for other cause, the central shaft of the furnace will stop revolving. The stoppage of the central shaft is not particularly noticeable to the attendant. If an arm carrying its rabbles happens to stop near the flame it is badly burned and warped and becomes unusable in a few minutes, if the attendant does not happen to notice it quickly and shut off the flame or start the furnace shaft revolving again.

To avoid the objections above referred to WQ-IDOUHILI a burner on the central hollow rotating shaft carrying the arms and rakes or rabbles, and we supply this burner with fuel, either pulverized coal or oil, which may be introduced either from the top or the bottom of the central rotating shaft. By mounting the burner on the rotating shaft the flame from the burner sweeps around the furnace chamber as the shaft revolves, and accumulations such as are above referredto are avoided; and as the burner is located at a point between the arms carrying the rakes or rabbles there is no danger of burning the same, should the rotation of the shaft be accidentally interrupted, as hereinbefore referred to.

Our invention is somewhat conventionally illustrated in the accompanying drawings in which Figure 1 illustrates one form of the invention in which the burner is to be supplied with pulverized coal introduced by air pressure from the top of the furnace. Fig. 2 is a partial view illustrating a construction in which an oil burner is employed, and in which the oil and air are introduced from the top of the furnace. Fig. 3 is a somewhat fragmentary view showing a modified form of the invention employing an oil burner, and Fig. 3 is a detail view showing a form of mixing chamber for the oil burner. Fig. 4.- is a detail view showing a construction whereby the fuel may be introduced to the rotating shaft from the bottom of the latter. Figs. 5 and 6 are detail views illustrating alternative forms of joints which may be employed between the stationary and rotating pipes in introducing fuel to the furnace.

Referring to the drawings, and more particularly just now to Fig. 1, 12 denotes the central hollow, rotating shaft of the wellknown type of roasting furnace as hereinbefore referred to, this shaft being in practice provided with arms 13 which carry the rakes or rabbles for causing the ore to be successively fed downward from the top of the furnace to the several hearths thereof, these hearths 141 being fragmentarily illustrated in dotted lines in Fig. 1. The arms 13, in practice, are air cooled, the air being supplied from a stationary or non-rotating pipe 15 communicating through a rotating pipe 16 which opens into an air manifold 17 rotatin with the shaft 12. The pipe 16 enters a bearing 18 supported by a beam 19, this bearing being properly packed to afford an air-tight joint. Mounted in a bearing 20 on the pipe 15 is a rotating fuel pipe 21 extending down the shaft 12 and communicating with a burner 22 projecting through the wall of the hollow rotating shaft 12, the said burner thus opening into the furnace chamber above one of the hearths of the furnace. Communicating with the pipe 21, through a stuffing box 23, is a stationary or non-rotating inlet pipe 2 1 through which pulverized coal and air may be introduced and carried through the pipe 21 to the burner 22.

Referring now particularly to Fig. 2 the stationary or non-rotating air inlet pipe 15 communicates with a rotating pipe 16 opening into the air manifold 17 The rotating pipe 16 has a bearing in a collar or part 18 which is supported by the beam 19, and is provided with stuiiing boxes 25 for affording tight joints between the stationary pipe 15, the rotating pipe 16 and the said bearing collar or part 18. Rotating with the pipe 16 and the hollow central shaft 12 are oil and air pipes 26 and 27 communicating with an oil burner 28 through pipes 29 and 30. The rotating oil pipe 26 communicates, through a stufiing boX 31, with a stationary or non-rotating oil inlet pipe 32, and the air inlet pipe 27 communicates with an air inlet pipe 33 through an annular chamber 34:

'lar or part 18 supported by the beam 19, as

in Fig. ,1; and in this form of the invention the stationary and nonrotating oil and air supply pipes 35 and 36 communicate with the rotating oil and air pipes 37 and 33 through the stufiing box 31 on the pipe 15. The oil pipe 37 communicates with the branch oil pipe 39, and the air pipe 38 communicates with a branch air pipe 10, these branch pipes 39 and -10 leading to the burner 31 through a mixing chamber afforded by a casing 12.

Instead of introducing the fuel from the top of the central rotating shaft of the furnace, as in the constructions above described, the fuel may be introduced from the bottom of the said central rotating shaft 12 as shown in Fig. 1- through a fuel pipe 43 passing through the bottom stepped bearing 44 of the said shaft 12, as illustrated in 1, and this fuel inlet pipe, which may be either for oil or pulverized coal, may rotate with said shaft, a tight joint between the said pipe and the said stepped bearingbeing afforded by a stufing box I Instead of using the joints thus far de scribed between the stationary and rotating fuel inlet pipes, the alternative forms of joints shown in Figs. 5 and 6 may be employed. In Fig. 5 the stationary pipe 46 is inside of the rotating pipe 17, with which latter the collar 18 and'the bushing a9 also rotate, a tight joint being afforded between the stationary and rotating pipes by the packing 50. In the construction shown in Fig. 6 the stationary pipe 51 is coupled to the stationary pipe 52, and the rotating pipe 53 is connected with a sleeve 54, and a bushing 55 which both rotate with said pipe, a tight joint being afforded by the packing 56.

From the foregoing it will be understood that, when the burner is in operation, as the central shaft 12 rotates the flame from the burner, which opens into the furnace chain-V her, will sweep in a circle around said chamber, thus evenly distributing the heat and avoiding accumulations on the hearths, as also avoiding danger of burning the rabble or rake arms, the burner being located between and away from said arms. T he burner may be located above any one of the hearths, and more than one burner may be employed, if desired. 6

The invention is not to be understood as being limited to the particular constructions herein shown and described, as the details of construction may be varied widely, within the province of mechanical skill, without departing from the spirit of the invention.

Having thus described our invention we claim and desire to secure by Letters Patent:

1. In a roasting furnace of the class described, the combination with a central hollow rotating shaft, of a burner mounted to rotate therewith and opening into the chamber of the furnace, and means for supplying fuel to said burner,-said means comprising oil and air supply pipes within and rotating with said shaft, stationary oil and air supply pipes, and packed joints between said rotating and stationary pipes.

52. In a roasting furnace of the class described, the combination with a central hollow rotating shaft, of a burner mounted to rotate therewith and opening into the chamber of the furnace, and means for supplying fuel to said burner, said means comprising oil and air supply pipes within and rotating with said shaft, stationary oil and air supply pipes, and packed joints between said rotating and stationary pipes, said oil pipe being within said air supply pipe.

3. In a roasting furnace of the class described, the combination with a central hollow rotating shaft, of a burner mounted to roate therewith and opening into the chamber of the furnace, and means for supplying fuel to said burner, said means comprising ber of the furnace and means for supplying fuel to said burner, said means comprising oil and air supply pipes within and rotating with said shaft, stationary oil and air supply pipes, packed joints between said rotating and stationary pipes, said oil pipe being within said air supply pipe, and branch oil and air supply pipes, the former within and surrounded by the latter, between the main oil and air supply pipes and said burner.

In testimony whereof we aiiix our signatures.

HARRY ALLEN CLARK.

JOHN FRANCIS HILL.

ALEXANDER GRANT McGREGOR. 

